Former IRA informer Martin McGartland, who survived an assassination attempt eight months ago, yesterday said he would fight police attempts to move him out of a safe house where he has been under 24-hour armed protection.

Northumbria Police want him take up a new identity in another part of the country or accept 28 days' notice to find "alternative accommodation".

Reports have put the cost of providing 24-hour protection for Mr McGartland at more than a pounds 1 million.

The force declined to comment on reports that assistant chief constable Tony Crimmens had written to the ex-RUC agent last week with the ultimatum.

Mr McGartland is credited with saving 50 lives, including those of British servicemen, when he infiltrated the IRA in Belfast between 1988 and 1991.

He believes it was the IRA who last June tried to have him killed outside his home on Tyneside, where he moved after his cover was blown in 1991.

He was shot six times, but Northumbria Police have refused to say whether the shooting was linked to the IRA.

Mr McGartland said the alternatives being offered by police did not guarantee his safety, and he would be seeking a judicial review of the decision.

He said: "The law clearly states that if there has been any threat against any individual, the police have a duty to look after that person to such times as that threat goes.

"I know it was the IRA that tried to shoot me last year, even though Northumbria Police refuse to say that, and my life is still in danger.

"What is being offered to me does not guarantee my safety. The IRA could easily uncover any new identity the Crown authorities give me, and the move to new accommodation does not provide me with even CCTV security."

He said: "People forget that I fought on behalf of the Government and the RUC by getting inside the IRA, even if is was for only two years.

"At the end of the day, I put my life on the line, and now they are saying, `okay that was a long time ago you have nothing to fear'. But I have been shot since."

The letter from Mr Crimmens claims McGartland has put his own life and those of his armed escorts at risk by slipping away from the safe house on at least one occasion.

McGartland said the police were using the incident to force him out.

A Northumbria Police spokeswoman said the force was not commenting on Mr McGartland's security arrangements.

But a force spokesman said: "We consider it unreasonable to provide the current level of accommodation and security on a long-term basis."

Mr Andrew Mackay, Conservative spokesman on Northern Ireland, said: "Clearly, McGartland is at risk, particularly after the attempt on his life last year.

"In those circumstances it is essential that he is properly protected by the authorities, and if this were not to be the case those responsible for such a decision would be in dereliction of their duties."